Encoded program cannot be decoded

[uncomputable]

trafficstars

Calling encode_to_vec and then RedeemNode::decode on the following program leads to a type unification error.

See https://github.com/BlockstreamResearch/simfony/issues/118

Decode(Type(Bind { existing_bound: { tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × ({ tmr: fd75bcd8cb55a5e424e09288ac8eb42942534ec1099b72bece0ea2c5479bf3e7, bit_width: 64, bound: 2^64 } × (... × ...))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))), new_bound: { tmr: 50b38cd76475ff8929288bfcd0d9df0e4a241c0a5708572ad264192a4fe67bee, bit_width: 0, bound: 1 }, hint: "comp combinator: left target = right source" }))

The Simplicity program is obtained by compiling the following Simfony program:

fn main() {
    let (a, b): (u32, u32) = (0, 1);
    assert!(jet::eq_32(a, 0));

    let (c, d): (u32, u32) = (2, 3);
    assert!(jet::eq_32(c, 2));
    assert!(jet::eq_32(d, 3));
}

Calling encode_to_vec yields the following hex string (unpruned, without debug symbols):

e2a4d900000000022c8000000041805481420c31206b1566dc41180459000000010342c80000000c1a82a40a05bf203601acfc10c13481c040e0027063f0c040b480a0dc170601903888

The fact that the encoding is broken makes it hard to describe the problematic Simplicity program in this issue. For now, the Simfony compiler must be used to obtain it.

For now, the code to reproduce the error lives on this Simfony branch. Run cargo test --all-features.